employ vs preengage

employ

verb
  • To make busy. 

  • To hire (somebody for work or a job). 

  • To use (somebody for a job, or something for a task). 

noun
  • The state of being an employee; employment. 

preengage

verb
  • To engage previously. 

How often have the words employ and preengage occurred in a corpus of books? (source: Google Ngram Viewer )